1. Field of the Invention
The present invention relates to powder supply devices and image forming apparatuses.
2. Description of the Related Art
Toner supply devices, which supply toner required for carrying out image forming, are provided in image forming apparatuses. Toner containers, which store toner for carrying out image forming, are provided in toner supply devices.
One type of toner supply device is a toner supply device that is employed in image forming apparatuses capable of color printing. There is a developing agent replenishing device (toner supply device) of this type of toner supply device that stores developing agents (toner) of multiple different colors for carrying out color printing.
Toner supply devices are provided with functions such as the following. Here, functions are shown of a toner supply device that stores toner of multiple different colors as one example of these functions. The toner supply device is provided with toner hoppers for storing toner of each color (for example, black, yellow, cyan, and magenta). A transport spiral for toner transport and a stirring paddle for toner stirring are provided inside each toner hopper. The toner stored in the toner hopper is transported in a transport spiral direction while being stirred by rotation of the stirring paddle. The toner that is transported in the transport spiral direction gathers near a toner supply opening due to rotation of the transport spiral. And toner is supplied from the toner supply opening to a developing section.
Incidentally, greater compactness and lower prices are sought for in image forming apparatuses. Accordingly, methods have been employed aiming to provide compactness and reduce costs in toner supply devices by using a single drive source to drive multiple stirring paddles, thereby reducing the number of drive sources.
However, when there is a single drive source, all the stirring paddles rotate simultaneously even when image forming is carried out using only black toner for example (monochrome printing). In this case, the toners of colors other than black are stirred unnecessarily. Excessive stirring of toners in this manner incurs toner deterioration and is a cause of image degradation. Further still, power consumption is increased since a load is placed on the drive source to no purpose.